How do I get my wired Sentinel & Vanguard to give clear pictures?

[sashaeagle]

   The help I've seen for this problem addresses interference with wireless cameras.  I have a quad plexor, 1 sentinel, 2 vanguards and a nightwatch (all wired).  Guess what, ... the only one of the four that gives a clear picture is the nightwatch.  I'd sure appreciate some ideas.  Thanks in advance.  Viki

[TrinityEB]

Can you better define what about the picture isn't clear?  Is is "out of focus" or blurry, are you getting static or is the picture wavy or jumping, etc...
Also, how far are the cameras from the quad and what kind of wire/connections are you using between the camera and quad?